If one person is honest and shares a challenge they’re having in the relationship, the other person exclaims in pain and horror, “How could you say something like that to me?!” This is a defensive maneuver that is designed to shut down any sort of scary or uncomfortable conversations. Nine times out of ten it will work in the short term, especially if the person bringing up the complaint is nice. They will feel bad for bringing up their challenge and stuff it back down, going into apology and damage control mode.